/Engine/Source/Editor/GraphEditor/Public/SGraphNode.h
Called from drag drop code when a disallowed connection is hovered
void NotifyDisallowedPinConnection ( const class [UEdGraphPin](API\Runtime\Engine\EdGraph\UEdGraphPin) * PinA, const class [UEdGraphPin](API\Runtime\Engine\EdGraph\UEdGraphPin) * PinB ) const